Field of the Invention
The present invention relates to a driving force transmission mechanism for transmitting and outputting an output force of a driving section via a drive gear and a driven gear.
Description of the Related Art
Heretofore, in a vehicular air conditioning apparatus, which is mounted in a passenger vehicle, cool air that is cooled by an evaporator serving as a cooling means and warm air that is heated by a heater core serving as a heating means are mixed together in a housing thereof by adjusting a degree of opening of an air mixing damper, and such mixed air is blown out selectively by opening and closing outlet doors, which are provided with respect to outlet ports disposed in the vehicle compartment. The air mixing damper and the outlet dampers include shafts that are axially supported with respect to the housing, such that by rotating the air mixing damper and the outlet dampers by given angles about the shafts, a mixing ratio of warm air and cool air or an opened/closed state of the outlet ports can be switched.
With the aforementioned vehicular air conditioning apparatus, for example, at a time of opening or closing the air mixing damper or the outlet dampers, a driving force transmission mechanism is used, which is capable of transmitting a driving force of a drive source to the air mixing damper, etc., through a plurality of gears.
For example, as disclosed in Japanese Laid-Open Patent Publication No. 2001-147060, such a driving force transmission mechanism is equipped with a drive gear connected to a drive source, a first transmission gear enmeshed with a small gear on the drive gear, a second transmission gear enmeshed with a second gear on the first transmission gear, and an output gear enmeshed with the second transmission gear and to which a driving force from the drive gear is transmitted. The output gear comprises one fat tooth, a tooth thickness of which is comparatively thick. The fat tooth enmeshes with a gear groove formed in a long tooth region of the second transmission gear where the gear width is comparatively long.
However, with the driving force transmission mechanism according to the prior art, in the case that a clearance is set such that an enmeshed state between the plurality of teeth provided on the small gear of the output gear, the tooth thickness of which is small, and the teeth provided on the second transmission gear, i.e., a mutually enmeshed state (hooked state) between the teeth, is made appropriate, meshing (hooking) between the fat tooth of the output gear and the second transmission gear becomes insufficient, and proper transmission of the driving force cannot be realized.